Korean ethylene plant reaps benefits from APC

LG Chem is Koreas first and largest vertically
integrated chemical company. Founded in 1947, the company has
emerged as one of the
worlds top 30 chemical makers. LG Chem produces a variety
of chemical products ranging from petrochemicals to specialty
chemicals, as well as electronic materials.

Last year, ARC interviewed Mr. Chang-Hoon Kang, project manager at the Petrochemicals Divisions
Daesan ethylene plant. Mr. Kang told us that, previously, the
plant had problems meeting corporate goals due to a variety of
issues such as variability of feedstock quality. However, using an
advanced process control-based (APC) solution, the engineering
team solved the problem to achieve plant operational stability,
increase production, and decrease energy consumption. In doing
so, the benefits more than paid for the investment.

Plant operations needed stability.

LG Chems Daesan ethylene plant is an important asset
in LG Chems Petrochemicals unit. The plant was
experiencing difficulty in meeting its corporate operations
goals due to a variety of issues. The naphtha feed typically
varies considerably in quality, and the plant has issues
related to furnace decoking, and tank and dryer swings. Since
ethylene crackers are major energy-consuming units, the
dynamics of the process further prohibited any attempts at
comprehensive energy management. This all contributed to a
process that was seldom in steady state.

Through a quality improvement program called
gaisen, the company had previously improved the
process, more than doubling the capacity from 350,000 tpy to
the current world-class capacity of 760,000 tpy. The underlying
problems, however, continued to cause plant upsets, resulting
in total productivity well below corporate expectations.

To have a chance at meeting corporate goals, the company
realized that it must stabilize operations before it could
concentrate on maximizing plant throughput, which is why the
company invested to increase the plants capacity in the
first place. Another LG Chem objective was to minimize energy
consumption to produce ethylene.

LG Chem realized there was only so much improvement that
could achieved with process and procedure changes. The company
had some success at its Yosu plant using multivariable control,
and the plant manager at Daesan was keen on trying to adopt
this approach. LG Chem chose to work with AspenTech. Together,
the two companies decided that the plant needed to go further
than just applying multivariable control to the 11 ethylene
cracker furnaces. The solution needed to be integrated with the
ethylene and propylene recovery areas downstream of the
furnaces. Due to the plantwide scope, inherent feedstock variations and other
disturbances, they decided to incorporate the Composite Linear
Program (CLP) tools with Aspen DMCplus. LG Chems LGSim
ethylene furnace model was used to create an online model for
composition and severity for the CLP and multivariable
controllers.

Since this was the plants first experience at such a
comprehensive change in automation, it had to be established
through proper leadership to help people understand the coming
changes. For example, the changes in the way the operators
managed the process required quick adoption of new methods.
Getting the employees, from operators to engineers, to work
together as a team was an important challenge to overcome early
on.

This was to be an integrated approach to automation; so they
had to establish effective connectivity between the existing
distributed control systems (DCSs) and the new APC and
optimization solution. In addition, since success relied on
accurate and highly available instrumentation, they had to
incorporate strategies to deal with any instrument failures
quickly.

Lessons learned and overall benefits.

LG Chem learned that it was possible to do such a large
scope project in a short period (eight
months) and within budget. This was possible partly due to the
team had secured senior managements backing early in the
project scope and partly because the project team included three members
from the supplier and three LG Chem employees. Including LG
Chem personnel on the team continues to help, as these team
members can make the necessary minor adjustments themselves
over the course of the year. If a big issue arises, then they
can organize a task force quickly and, if necessary, call in
AspenTech under their annual maintenance agreement.

LG Chem is very satisfied with the stable operation provided
by the advanced automation. The APC has a 90% service factor
and drives the unit operations to the appropriate constraints.
Management and operating personnel alike are now armed with key
performance indicators and other performance information to
help everyone stay on the productivity path.

LG Chems eight-month effort and $400,000 expenditure
resulted in a 2% increase in ethylene and propylene production.
The stabilization of the plant reduced total energy consumption
by 1.5%. Combined, this represents the equivalent of about $4
million
in annual benefits. HP

The author

Dick Hill is vice president of
ARC Advisory Group, Dedham, Massachusetts,
responsible for developing the strategic direction
for ARC products, services and geographical expansion. He is
responsible for covering advanced software business
worldwide. In addition, he provides leadership for
support of ARC's automation team and clients. Mr.
Hill has over 30 years of experience in manufacturing
and automation. He has broad international experience
with The Foxboro Company. Prior to Foxboro, Mr. Hill
was a senior process control engineer with BP Oil,
developing and implementing advanced process control
applications. Prior to joining ARC, he was the US
general manager of Walsh Automation, a major
engineering consulting firm and supplier of CIM
solutions to the pulp and paper, petrochemicals,
pharmaceutical, and other process and manufacturing
industries. He is a graduate from Lowell
Technological Institute with a BS degree in chemical
engineering.

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